The Gordon Research Conferences bring together the most active researchers in a given area of research for the purpose of in-depth discussion, including the exchange of new and unpublished ideas and technology, that will strengthen research efforts in the field. The 1991 Conference on Hormone Action represents the 22nd conference in the series. The conference will continue to provide a forum for the latest advances in molecular and cellular endocrinology. Sessions on hormonal regulation of gene expression will focus on steroid hormones as general models for the hormonal control of transcription, as well as emphasizing recent structure/function studies of various members of the steroid receptor gene family. Recent exciting advances in our understanding of the signal transduction pathways employed by other classes of hormones will focus on events occurring at the cell membrane, as well as the role of different protein kinases, tyrosine phosphatases and calcium in regulating gene expression. A related session will deal with the hormonal regulation of development in Dictyostelium, Drosophila, Xenopus and mammalian cells. Recent advances in neuroendocrinology will be covered, as well as the mechanism of action of growth factors and oncogenes studied in transgenic mouse models. A session on the structure and function of several members of the newly discovered hematopoietin receptor gene family has been included. Finally, three outstanding plenary lectures will introduce topics of interest to investigators studying hormone action. This conference brings together an unusually diverse group of individuals ranging from basic scientists studying molecular mechanisms of hormone regulation, to physiologists and physician scientists interested in the integrative actions of hormones and their application to human disease. The limited attendance policy coupled with highly successful poster sessions, in which both younger scientists and senior investigators present their unpublished work, provides a unique forum for an exchange of ideas. The Gordon Conference Foundation generously supports these conferences, but cannot provide sufficient funds to cover most major expenses of speakers. Solicitation of private funds is not permitted. Therefore sources of support such as the National Institutes of Health are critical to the continuing success of the conference.